This invention relates to an improvement in an absorption system hot and cold water supply apparatus of the type for simultaneously supplying hot and cold water by forming a circulation path for a refrigerant and an absorbent solution, providing a generator with a water heater and defining a refrigerant circulation path between these devices.
An absorption system hot and cold water supply apparatus of the type described above is disclosed, for example, in Japanese Patent Publication No. 52-584/1977 (corresponding to U.S. Pat. No. 3,837,174). The apparatus of this prior art reference includes a capacity controller (thermocapacity controller) for controlling the quantity of heat of a generator by a cold or hot water temperature or for controlling the quantity of heat in combination with the control of a refrigerant flow rate, for example, and includes also a protective thermostat in a cold water conduit so that this thermostat stops the operation of a pump for refrigerant solution at a specific cold water temperature (e.g. 3.degree. C.) and the thermo-capacity controller stops heating of the generator at a temperature lower than this specific cold water temperature.
In the absorption system hot and cold water supply apparatus for simultaneously supplying the hot and cold water of the type described above, however, the quantity of heat from the generator must be regulated in proportion to a hot water load when the hot water load is large but a cold water load is small. Accordingly, the cold water output for the cold water load, that is, the evaporation capacity of the refrigerant in the evaporator, that is, the refrigerant absorption capacity of the absorbent solution in the absorber or, in other words, the degree of concentration of the absorbent solution inside the generator, is likely to become excessively high and hence freezing of the refrigerant or the cold water is likely to occur in the evaporator.
Therefore, the conventional absorption system hot and cold water supply apparatus described above employs a method which stops the operation of the refrigerant pump by a protective thermostat disposed in a cold water conduit at a specific cold water temperature, stops the concentration of the absorbent solution at a lower temperature than this specific temperature by cutting off heating of the generator and prevents the freezing of the cold water. However, this method needs a considerable time for the concentration of the absorbent solution in the absorber to drop or in other words, for the saturation temperature in both the evaporator and the absorber to rise to a normal value, so that the problems such as freezing of the refrigerant and the cold water at the time of the temperature drop of the cold water, for example, and crystallization of the absorbent solution cannot be prevented. Since heating of the generator must often be cut off in order to prevent the freezing, the hot water output to the hot water load becomes unstable and insufficient.